Lapping machine



p 6, 1943. H. s. INDGE 2,315,859

LAPPING MACHINE Filed Jan. 24, 1941 2 Sheets-Sheet 1 HERBERT S. INDG'EPatented Apr. 6, 1943 LAPPIN G MACHINE Herbert S. Indge, Westboro,Mass., assignor to Norton Company, Worcester, Mass., a corporation ofMassachusetts Application January 24, 1941, Serial No. 375,828

4 Claims.

The invention relates to lapping machines, and more particularly to amachine for lapping the lapped side faces of piston rings and the like.

One object of the invention is to provide a simple and thoroughlypractical lapping machine. Another object of the invention is to providea lapping machine in which a ringshaped object is rotatably supportedwhile it is lapped by a rapidly reciprocating abrasive lapping element.A further object of the invention is to provide a hydraulically operatedreciprocable lapping element which is adjustably supported so that itmay lap either a plane side face of a work piece normal to its axis ofrotation or an angular or tapered face thereon such as,

for example, a piston ring tapered cross section.

Another object of the invention is to provide a piston ring lappingmachine in which a pair of independent hydraulic motors are arranged toreciprocate lapping sticks in engagement with a side face of a workpiece, such as a tapered pision ring, in diametrically opposedpositions. A further object of the invention is to provide such alapping machine in which the hydraulic motors and lapping stickssupported thereby are independently and angularly adjustable.

Another object of the invention is to provide a lapping machine having amotor driven rotatable work support and a hydraulically operab'ie slidefor supporting a plurality of hydraulically reciprocated lappingelements, in which a manually operable main control valve serves tocontrol the positioning of the lapping sticks and automatically tocontrol the stopping and starting of the work driving motor, Otherobjects'will be in part obvious or inpart pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, as will beexemplified in the structure to be hereinafter described, and the scopeof the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possibleembodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of the improved 7 lapping machine, havingparts broken away and the lapping heads, taken approximately on the line3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional view through one of the lapping heads.taken approximately on the line 4--4 of Figs. 1 and 3;

Fig. 5 is a fragmentary cross-sectional viewthrough the lapping head ofthe machine, taken approximately on the line 5-5 of Figs. 1 and 2;

Fig. 6 is 'a fragmentary cross-sectional view, on an enlarged scale,taken approximately on the line 56 of Fig. 1;

Fig. 7 is a cross-sectional view, taken approximately on the line 'I'lof Figs. 3 and 4;

Fig. 8 is a fragmentary cross-sectional view, taken approximately on theline 8-8 of Fig. 7;

Fig. 9 is a fragmentary cross sectional view of a modified construction,in which the fluid pressure is used to move the lapping element to andfrom an operative position; and

Fig. 10 is a fragmentary diagrammatic view showing the lapping elementsarranged simultaneously to lap adjacent angularly disposed faces on awork piece.

A lapping machine has been shown in the drawings, comprising a base [0which supports a rotatable work support, such as a work head H. The workhead it is mounted on the upper surface of the base l0 and is providedwith a rotatable spindle l2 which is supported in antifriction bearingsI3 and M. The spindle l2 supports a chuck, such as a face plate l5,which is recessed so as to support a work piece, such as a piston ringis.

The spindle i2 is preferably rotated by a motor driven mechanism,comprising a variable speed electric motor l7 mounted within the workhead I I. The motor ii is provided with an armature shaft |8 whichsupports a V-groove pulley 19. The pulley I9 is connected by means of aV-belt 20 with a V-groove pulley 2| mounted on the end of the spindle12.

Power is supplied for the motor I! by a suitable outside source, asrepresented by the power lines 22.(Fig, 1). A snap switch 23 is providedto open and close the circuit controlling the motor I1. A variable speedrheostat 24 is provided for manually controlling the speed of the motorI! so as to thereby regulate and control the speed of rotation of thework piece I 6. A normally closed limit switch 25 is connected in serieswith the snap switch 23 and the rheostat 24 by means of which theelectric circuit controlling the motor ll may be opened automatically tostop the rotation of the work piece l6 after a lapping operation hasbeen completed in a manner to be hereinafter described.

A transversely moveable lap supporting slide 30 is provided forsupporting the lapping element to be hereinafter described. Theslide 30is provided with a dovetailed slideway 3| which mates with acorrespondingly shaped way 32 which is fixedly mounted on the upper faceof the base H). The slide 30 is arranged so that it may be moved to andfrom an operative position to facilitate loading of work pieces andremoving them from the machine before and after a lapping operation.

In the preferred construction, a hydraulically operated mechanism isprovided for moving the slide 30 transversely in either direction, whichmay comprise a cylinder 33 which is fixedly mounted within the base llof'the machine. The cylinder 33 contains a slidable piston 34 which isconnected to one end of a piston rod 35. The other end of the piston rod35 is connected to a bracket 35v which projects downwardly from theunder side of the slide 35, It will be readily ap parent from theforegoing disclosure that when fluid under pressureis admitted to acylinder chamber 31 at the left-hand end of the cylinder 33 (Fig. 1),the piston 34 together with the piston rod 35 and the bracket 35 willmove the slide 30 toward the right. Similarly, when fluid under pressureis admitted to a cylinder chamber 38 at the right-hand end of thecylinder 33 (Fig. 1), the piston 34 together with the piston rod 35 andthe bracket 35 will move the slide 30 toward the left (Fig. 1).

A fluid pressure system is provided for conveying fluid under pressureto the cylinder 33 and also to other fluid pressure actuating mechanismsto be hereinafter described. A box-like reservoir 40 is provided withinthe base I of the machine. Fluid is pumped from the reservoir 40 bymeans of a motor driven fluid pump 4|. Fluid is drawn by the pump 4|through a pipe 42 and conveyed through a pipe 43 to a manually operablecontrol valve 44. An adjustable pressure relief valve 45 is connected bya pipe 46 with the pipe 43. The pressure relief valve 45 is adjusted tomaintain the desired operating pressure within the fluid pressure systembut is so arranged as to allow excess fluid under pressure to exhaustthrough a pipe 41 into the reservoir 40.

The control valve 44 is a piston type control valve comprising a valvestem 50 having formed integrally therewith valve pistons 52, 53, 54, 55and 55. The valve 44 is arranged so that it may be actuated manually bymeans of a manually operable control lever 51 which is pivotallysupported on a stud 58 which is in turn fixedly supported on the machinebase ID. The lower end of the lever 51 is yoke-shaped and is providedwith diametrically opposed studs or pins 59 which engage a groove 60formed in the valve i stem 50. The valve stem 50 is shown in its extremeright-hand end position (Fig. 1), in which position the slide 30 ismoved toward the left into an operative position. In this position ofthe parts, fluid under pressure passing through the pipe 43 passesthrough a pipe 6| into a cylinder chamber located between the valvepistons 54 and 55 and passes out through a pipe 62 into the cylinderchamber 38 to move the piston 34, the piston rod 35, the bracket 36, andthe slide 30 toward the left to position the lapping elements to behereinafter described in an operative position for a lapping operation.During the movement of the slide 35 toward the left, fluid within thecylinder chamber 31 exhausts through a pipe 53, through a valve chamberformed between the valve pistons 53 and 54, and exhausts through a pipe64 into the reservoir 40. A throttle valve 35 is provided in the pipeline 34 to facilitate control of the exhausting fluid from the cylinder33 so as to control the speed or rate of movement of the slide in eitherdirection. An adjustably positioned stop block 55 is provided to limitthe forward movement or movement of the slide 30 toward the left (Fig.l)

After a lapping operation has been completed and it is desired to movethe slide 30 to a rearward or inoperative position, the control lever 51is moved in a clockwise direction (Fig. 1) into the broken line position51a, which movement is transmitted to shift the control valve 44 towardthe left (Fig. 1). In the left-hand end position of the valve 44, fluidunder pressure from the pipe 43 passes through the pipe 6| into thevalve chamber formed between the valve pistons 54 and 55 and passesoutwardly through the pipe 33 into the cylinder chamber 31 to move thepiston 34, the piston rod 35, the bracket 36 and the slide 30 toward theright (Fig. l) to an inoperative position.

In the production of work pieces, such as relatively large diameterpiston rings for the automotive and aeroplane engines, it is desirableto provide a highly finished surface on the flat side faces of the ring.This is preferably accomplished by mounting the ring |6 in position onthe face plate l5 and providing one or more reciprocable lappingelements to reciprocate in a substantially radial path across the sideface of the ring l5 as it rotates to provide an ultra-refined surface onthe side face of the ring Hi. In the preferred construction, a pair oflapping heads 61 and 68 are provided having reciprocable lapping sticks69 and 10, respectively, the ends of which are arranged to engage theside face of the piston ring Hi to be lapped at diametrically oppositepositions. A single lapping head may be utilized, if desired, or aplurality of heads may be provided, such as the two heads shown in thedrawings, whereby an increased lapping action may be produced toincrease the productive output of the machine. The lapping sticks 59 and10 may be of any cross-sectional shape but for the sake of illustrationhave been shown as being of a square cross-sectional area made of bondedabrasive material and arranged so that the end face of the stick engagesfor a lapping operation the side face of a piston ring IS.

The lapping stick 10 is adjustably supported in a slide block 1| whichis arranged to slide between a pair of opposed guide plates 12 and 13(Figs. 4 and 7). The lapping stick 10 is held in adjusted position inthe slide block 1| by means of a pair of set screws 14 and 15 which arescrew threaded into an end plate which is fixed to the slide block 1|The screws 14 and 15 bear against a shim 16 (Fig. '1) which in turnclamps the lapping stick 10 in adjusted position in the slide block 1|.

A hydraulic motor 11 is provided to impart a reciprocatory movement tothe lapping stick 10. The motor 11 will not be described in detail,since it is identical with that shown in the prior U. S. patent toWallace H. Wood, No. 2,212,371 dated August 27, 1940, to which referencemay be had for details of disclosure not contained herein. 'Thehydraulic motor 11 comprises a cylinder 13 (Fig. '7) which contains aslidabl piston 19.

The piston 19 is connected to one end of a piston rod 80, the other endof which is connected to theslide block II. The motor 11 is providedwith a control valve comprising a hollow pilot valve 8| which contains aslidably mounted shuttle type reversing valve 82. The pilot valve 8| isprovided with a valve stem 83 having a pair of adjustable dogs 84 and 85mounted thereon. The dogs 84 and 85 are arranged in the path of a lug 86which projects from the slide block 1I and serves automatically to shiftthe pilot valve M to reverse the motor 11. It will be readily apparentfrom the foregoing disclosure that when the piston 18 is moved back andforth within the cylinder 18, a reciprocatory movement will be impartedto the slide block 1| and th abrasive lapping stick 10.

Fluid under pressure from the control valve 44 passes through a pipe 88into a chamber 89 (Fig. 8) in the casing surrounding the pilot valve 8|and through ports into a valve chamber. Fluid is exhausted from themotor 11 through a passage 90 and a pipe 9| into the reservoir 40.

and passes out through a pipe 94 which connectswith the pipe 88 toconvey fluid under pressure to the hydraulic motor 11 (Fig. 1)

Similarly, the lapping head 61 is provided with a hydraulic motor 91 forreciprocating the lapping stick 69 in operative lapping contact with thework piece IS. The motor 91 is identical with the hydraulic motor 11,consequently it has not been illustrated in detail. For details ofdisclosure not contained herein, reference may be had to the hydraulicmotor 11 and to the prior U. S. patent to Wallace H. Wood, No. 2,212,871dated August 27, 1940. Th motor 91 is provided with a pilot valve whichis actuated by a valve stem 98 (Fig. 1). The valve stem 98 is providedwith a pair of adjustable dogs or collars 99 and I which are arranged inthe path of a lug IOI which projects from the slide block supporting thelapping stick 69. Fluid under pressure passing through the pipe 94passes through a pipe I02 to provid pressure for actuating the motor 91to impart a reciprocatory movement to the lapping stick 69. Fluid isexhausted from the motor 91 through a pipe I03 which exhausts into thereservoir'40. A throttl valve I04 is provided in the pipe line I03 bymeans of which the speed of the hydraulic motor 91 and the speed ofreciprocation of the lapping stick 69 may be readily varied andcontrolled.

In the position of the parts as shown in Fig. 1, fluid under pressurefrom the pipe 43 passes to each of the hydraulic motors 11 and 91continuously to reciprocate the lapping sticks and 69,.

respectively, rapidly across the end face of the piston ring I6 to lapthe same during rotation thereof. After a lapping operation has beencompleted and the valve control lever 51 is shifted into position 51a,the valve piston 52 closes the port at the end of th fluid pressure pipe93, thus cutting oiT fluid under pressure from the pipe 94simultaneously to stop the hydraulic motors '11 and 91.

The hydraulic motors 11 and 91, together with the lapping sticks 10 and69, respectively, supported thereby. ar arranged so that they may bemoved to and from an operative position and-so that the lapping sticks10 and 69 may be maintained yielda-bly in engagement with the surfacebeing lapped. As illustrated in the drawings, the motor 11 is mounted onthe end of a piston rod I06. The other end of the piston rod I05 isprovided with a piston I06 which is slidably mounted within a cylinderI01. The piston rod I05 is provided with a central aperture I09. Aspring I09 is contained within the aperture I08 and is interposedbetween the end of the aperture I08 and a slidably mounted plug IIO. Anadjusting screw III is screw threaded through an end cap H2 and servesto facilitat adjustment of the compression of the spring I09 whereby thepressure of the lapping stick 10 on the piston ring I6 may be varied asdesired.

The piston rod I05 is held against any rotary movement by means ofa-guide bar H3 which is fixedly mounted on the outer surface 01' thecylinder I01. The guide rod or bar II3 passes through a correspondinglyshaped aperture H4 formed in or fixedly mounted on the casing of themotor 11. The guide bar H3 is provided with a depending lug II5which'supports a stop screw H6. The stop screw H6 is engaged by aportion of the motor casing 11 and serves to limit the forward advancingmovement of the motor 11 and the lapping stick 10 so as to accuratelylimit the advancing movement of the lapping stick 10. After a lappingoperation has been completed, fluid under pressure may be admittedthrough a pipe II1 into a cylinder chamber I18 to cause the piston I06together with the motor 11 and lapping stick 10 to move toward the right(Fig. 1) against the compression of the spring I09 to move the lappingstick 10 out of operative engagement with the work piece I6 beinglapped.

Similarly, the fluid motor 91 is mounted on the left-hand end of apiston rod I 20. The piston rod I 20 is provided with a piston IZI atits other end which is slidably mounted within a cylinder I22. Thepiston rod I20 is provided with a central aperture I23 which contains acompression spring I24. The compression spring I24 is interposed betweenthe left-hand end of the aperture I23 and an adjustable slidably mountedplug I25. An adjusting screw I26 is screw threaded through an end capI21 which is fixedly mounted on the right-hand end of the cylinder I22(Fig. 1). The inner end of the screw I26 abuts against the plug I25. Byadjusting the screw I26, the compression of the spring I24 maybeadjusted as desired so as to provide the desired pressure of th lappingstick 69 on the face of the piston ring I6 being lapped.

In order'to prevent rotary motion of the piston rod I20 together withthe motor 91, a guide bar I28 is fixedly mounted to the outside of thecylinder I 22. The guide bar I28 extends within a correspondingly shapedaperture I29 formed in or fixedly mounted on the casing of the fluidmotor 91 so that the motor 91 may slide with the piston rod I20 withoutany rotary motion. The guide bar I28 is provided with an upwardlyextending lug I30 which carries a stop screw I3I. The stop screw I3I isarranged in the path of a portion of the'motor casing and serves tolimit the movement of the engagement with the piston ring 16 beinglapped, fluid under pressure is admitted through a pipe I32 into acylinder chamber I33 to move the piston I2I together with the piston rodI20, the hydraulic motor 91 and the lapping stick 68 in a directiontoward the right (Fig. 1). 7

The pipe I32 is connected to the pipe 1 which in turn is connected to athrottle valve I34 (Fig. l). The throttle valve I34 is in turn connectedby a pipe I35 with the main control valve 44. In the position of thevalve 44 (Fig. l), the pipe I35 connects with a valve chamber locatedbetween the valve pistons 52 and 53 which in the position shown isconnected to an exhaust pipe I36 leading to the reservoir 40. After agrinding operation has been completed and the valve stem 50 is movedtoward the left, the movement of the valve piston 53 toward the leftcloses the port leading to the exhaust pipe I36 and opens a port so thatfluid under pressure within the pipe 43 may pass through a pipe I31 intothe valve chamber located between the valve pistons 52 and 53 and passesoutwardly through the pipe I35 and the valve I34 simultaneously to movethe lapping sticks 68 and out of operative engagement with the pistonring I6 being lapped. The throttle valve I34 located between the pipes Iand H1 serves to regulate the passage of pressure to and from thecylinder chambers H8 and I33,

respectively, so that the rate of movement of the lapping sticks 10 and69, respectively, into engagement with the work may be readilycontrolled as desired.

It is desirable that the path of reciprocation of the lapping sticks 69and 10 be angularly adjustable in order that either a fiat or a taperedend face may be lapped on the piston ring I6 as desired. To accomplishthis desired result, the lapping heads 61 and 66 are adjustablysupported on the transversely movable slide 30. The transversely movableslide 30 is provided with a verti cally extending column I40 whichserves as a support for the lapping heads 61 and 68. The column I40 isprovided with a plurality of vertically arranged T-slots I5I, I52, I60and I6I (Figs. 1, 2 and 5). A rectangularly shaped plate I4I (Figs. 1and 2) is adjustably mounted on the column I40 by means of mountingscrews I42, I43, I44 and I45 and serves as a support for the lappinghead 68. The cylinder I01 of the lapping head 68 is formed integral witha sector-shaped plate I46 which is pivotally supported by a stud I41 onthe plate I. The sector plate I46 may be angularly adjusted in avertical plane relative to the vertically adjustable plate I4I. Aclamping screw I48 and the clamping screw I45 serve to clamp the plateI46 in adjusted position on the plate MI. The clamping bolt I45 has itshead slidably positioned in a T-slot I5I formed in the column I40 andpasses through a hole formed in the supporting plate HI and passesthrough an elongated slot I50 formed in the sector plate I46. Theclamping screw I48 passes through an elongated slot I49 in the sectorplate I46 and is screw threaded into the vertically adjustablesupporting plate I (Fig. 6). It will be readily apparent from theforegoing disclosure that the clamping bolt I45 serves jointly as abinding screw for both the sector plate I46 and the verticallyadjustable supporting plate I.

Similarly, a vertically adjustable supporting plate I is adjustablyclamped on the column I40 by clamping screws I56, I51, I58 and I59. Theclamping bolts I56, I51 have their heads supported in a verticallyarranged T-slot I60 formed in the column I40, and the clamping bolts I56and I58 have their heads supported in a T- slot I6I, also formed andarranged vertically on the column I40. A sector-shaped plate I62 isformed integral with the cylinder I22 of the lapping head 61. The sectorplate I62 is .pivotally supported on a stud I63. A binder or clampingscrew I64 passes through an elongated slot I65 formed in thesector-shaped plate I62 and is screw threaded into the verticallyadjustable plate I55. This serves as a means for clamping the sectorplate in adjusted angular position so that the path of reciprocation ofthe lapping stick 69 may be either normal to the axis of rotation of thepiston ring I6 being lapped in case a flat side face is desired or at anangle thereto as shown in the drawings for producing a, tapered sideface on the ring I6. The clam-ping screw I56 also serves as anadditional clamping medium for clamping the sector-shaped plate I62 inadjusted position.- The clamping screw I56 passes through an elongatedslot I66 formed in the sector-shaped plate I62 and passes through a holeformed in a vertical supporting plate I55. Its head is supported in theT-slot I6I so that when it is clamped in position it serves jointly tolock the sector plate in adjusted position on the supportingplate I55and also to lock the supporting plate I55 in position on the column I40.

If desired, the lapping sticks 69 and 10 may be moved into operativeengagement with the ring I6 to be lapped and maintained in lappingengagement therewith by means of fluid under pressure. A modification ofthe lapping head 68 has been illustrated in Fig. 9, in which fluid underpressure may be utilized for moving the piston I06 toward the left (Fig.9) to move the lapping stick 10 into an operative position. Fluid underpressure from the pump 4| (Fig. 1) in this case is conveyed through apipe I10 (Fig. 9), through a throttle valve Ill, a pipe I12, and amanually operable control valve I13, and through a pipe I14 into acylinder chamber I15 at the right-hand end of the piston I06. Fluidunder pressure within the pipe I14 may also pass through a pipe I16 tothe other lapping head simultaneously to move both of the lapping sticksinto an operative position. By regulation of the throttle valve I1I, thespeed of movement of the piston I06 may be varied as desired. After alapping operation has been completed, the valve I13 may be shifted intothe dotted line position (Fig. 9) so that fluid within the cylinderchamber I16 may exhaust through the pipe I14 and through a pipe I11which returns the exhausting fluid to the reservoir 40.

A spring-pressed detent I is provided having an arrow point operativeend which is arranged to mate with a V-groove I8I formed in the stem 50of the control valve 44 so that the lapping sticks 69 and 10 (Fig. 1)may be readily moved to an inoperative position in case it is desired toinspect the work piece being lapped. The contrcl lever 51 is moved intoposition 511) which shifts the valve stem 50 so that the groove I8I isaligned with and engaged by the spring-pressed detent I80, so that thevalve piston 53 moves a sufficient distance 'to cover the port to cutoff the pipe I35 from connection with the exhaust pipe I36. The movementalso shifts the valve piston 52 toward the left a sufficient distance sothat fluid under pressure from the pump 4I passing through the pipe 43passes through the pipe I31 and through the valve chamber locatedbetween the valve pistons 52 and 53 and out through the pipe I35simultaneously to provide fluid under pressure within the cylinderchambers H8 and I33, respectively, to move the pistons I06 and I2 I,respectively, toward the right (Fig. 1), which movement serves to removethe lapping sticks 10 and 69, respectively, from operative engagementwith the piston ring I6.

The detent I80 and groove I8I serve as a locating device so that theoperator may readily-shift the valve 44 into the intermediatepositionabove mentioned or may shift the control lever 51 into thereverse position 51a by merely overcoming the resistance of the detentI80 after a lapping operation has been completed to facilitate removalof the finish lapped piece of work and the insertion of a fresh piece ofwork to be lapped.

It is desirable to provide an interconnection between the hydrauliccontrol system for controlling and actuating the lapping sticks and theelectrical mechanism for, controlling the rotation of the work piece. Asillustrated in Fig. 1, the actuating plunger of the normally closedlimit switch 25 is arranged in the path of movement of the valve stem 50of the main control valve 44. As shown in Fig. 1, the parts areillustrated in an operative position with the work piece I6 rotating andthe lapping sticks in reciprocable engagement with the rotating workpiece. After the lapping operation has been completed, the control lever51 is shifted into position 51a to withdraw the lapping sticks 69 and Hifrom operative contact with the work piece I6, stop the reciprocation ofthe lapping sticks I and 69, and move the transverse slide 30 to aninoperative position so that the lapping heads 68 and 61 are moved to aninoperative position.

During the shifting movement of the control lever 51 into position 5111,the end of the valve stem 50 engages and moves the actuating plunger ofthe normally closed limit switch 25 so as to open the switch, thusbreaking a circuit automatically to stop the electric motor I! andthereby stop the rotation of the face plate I and the piston ring I6.Similarly, when a new piece of work has been inserted and it is desiredto start a lapping operation, the control lever 51 is shifted from thebroken line position 51a (Fig. 1) into the full line position 51, whichmovement shifts the valve stem 50 toward the right, thus withdrawing itout of contact with the actuating plunger of the normally closed limitswitch" which allows the switch to close, thus closing a circuit tostart the work driving motor I! to set the face plate I5 and piston ringI6 to be lapped in rotation automatically before the lapping sticks 69and I0 are in operative engagement therewith.

The operation of this improved lapping machine will be readily apparentfrom the foregoing disclosure. Assuming all of the adjustments to havebeen previously made, that is, the sector-shaped supporting plate I46and I62 angularly adjusted to position the reciprocatory stroke of thelapping sticks I0 and 69, respectively, a work piece, such as a pistonring I6, is inserted in position on the face plate I5, after which thecontrol lever 51 is shifted from broken line position 51a into full lineposition 51 (Fig. 1). This movement of the control lever shifts thevalve stem 50 into the position-shown in Fig. 1, which movement allowsthe normally closed limit switch 25 to close,thus closing a circuitautomatically to start the work driving motor I1 which in turn transmitsa rotary motion through the spindle I2 and face plate I5 to the pistonring I6.

The shifting of the valve stem so toward the right into the positionillustrating in Fig. 1 first serves to shift the valve piston 52 touncover the port leading to the pipe 94, thus admitting fluid underpressure through the pipe 88 and I02, re-' spectively, which conveyfluid under pressure to the hydraulic lapping stick motors I1 and 91,respectively, to start the reciprocatory movement of the lapping sticks10 and 69, respectively. The valve piston 55 then uncovers the portleading to the pipe 62 to admit fluid under pressure into the cylinderchamber 38 to move the piston 34 together with the transversely movablelap supporting slide 30 toward the left into engagement with the stopabutment 66 to position the slide in an operative position for a lappingoperation. Continued movement of the valve into its righthand endposition (Fig. 1) moves the valve piston 53 so as to uncover the portconnecting the pipe I35 with the exhaust pipe I36 so as to allow thefluid within the cylinder chambers H8 and I23, respectively, to beexhausted therefrom by means of the released compression of the springsI09 and I24, respectively, which movement serves to shift the lappingheads TI and 91 so that the lapping sticks I0 and 69, respectively, aremoved into operative lapping engagement with the piston ring I6 to belapped. It will be readily apparent from the foregoing disclosure thatthe lapping sticks I0 and 69 are reciprocating as they are moved intooperative engagement with the work piece I6. As previously described,the pressure of the lapping sticks 69 and I0 in engagement with the workmay be controlled by adjustment of the compression of the springs I09and I24, respectively.

After the lapping operation has proceeded to the desired extent, thecontrol lever 51 may be shifted into position 51a, which movement servesfirst to admit fluid under pressure to the cylinder chambers H8 and I23,respectively, to move the lapping sticks 10 and 69 out of operativecontact with the piston ring I 6, after which fluid under pressure iscut off from the pipe 94 to stop the hydraulic motors 11 and 91,respectively. and then finally fluid under pressure is admitted throughthe pipe 63 into the cylinder chamber 31 to move the piston 34 togetherwith the transversely movable lap supporting slide 30 transverselytoward the right (Fig. 1) to an inoperative position to facilitateremoval of the piston ring I6 which has been lapped. When the valve stem50 approaches its left-hand end position, its end engages the actuatingplunger of the normally closed limit switch 25 and opens the switch tobreak the circuit, thereby automatically stopping the work driving motorII, the face plate I5 and the piston ring I6. The lapped piston ring I6may then be readily removed and a new work piece, such as a piston ringI 6, inserted for the next lapping operation.

It will thus be seen that there has been provided by this inventionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as manychanges might be made in the embodiment I claim:

1. In a lapping machine having a base, a rotatable work support thereon,means to rotate said work support, a transversely movable slide on saidbase, a vertically adjustable support on said slide, an adjustableswivel plate on said adjustable support, a lapping head carried by saidplate comprising a piston and cylinder, an adjustable spring to movesaid piston in one direction, a fluid pressure system whereby the pistonmay be moved in the other direction by fluid under pressure, a pistonrod having one end fixedly attached to the piston, a self-containedfluid motor fixedly mounted on the other end of said piston rod, and alapping element adjustably mounted to be reciprocated by said motorwhile in operative engagement with a work piece.

2'. In a lapping machine having a base, a rotatable work supportthereon, means to rotate said work support, a transversely movable slideon said base, a vertically adjustable support on said slide, anadjustable swivel plate on said adjustable support, a, lapping headcarried by said plate comprising a piston and cylinder, an adjustablespring to move said piston in one direction, a fluid pressure systemwhereby the piston may be moved in the other direction by fluid underpressure, a piston rod having one end fixedly attached to the piston, aself-contained fluid motor fixedly mounted on the other end of saidpiston rod, a lapping element adjustably mounted to be reciprocated bysaid motor while in operative engagement with a work piece, and means toadjust the reciprocatory stroke of said fluid motor and lapping element.

8. In a. lapping machine having a base, a retatable work supportthereon, a transversely movable slide on said base which is arranged tomove in a direction parallel to the axis of said work support, a pair orlapping heads adjustably mounted on said slide each having areciprocable lapping element which are arranged to engage a work pieceat diametrically opposite points, means independently to adjust each ofsaid heads toward and from the axis of the work support, a fluid motorand a control valve therefor on each of said heads rapidly toreciprocate said lapping elements, andindependent means to adjust eachof said heads angularly and in a plane normal to the axis of said worksupport so that adjacent angularly disposed faces on a work piece may besimultaneously lapped.

4. In a lapping machine having a base, a rotatable work support thereon,a transversely movable slide, a pair of lapping heads on said slide eachhaving a reciprocable lapping element arranged to engage the work pieceat diametrically opposite positions, independent fluid motors on each ofsaid heads rapidly to reciprocate said elements in a path substantiallynormal to the axis of the work support, means independentiy to adjusteach of said heads toward and HERBERT S. INDGE.

